The objective of the original grant application was to study the interaction of collagenase-isolated adult rat hepatocytes with viruses in order to achieve the two separate but related goals of determining (1) the effect of virus infection and transformation on expression of differentiated liver cell functions, and (2) the influence of a differentiated nonproliferating adult hepatocyte on virus replication. Three independently isolated SV40-transformed hepatocyte cell lines were innoculated s.c. into newborn syngeneic animals. One cell line, SV40hpI, produced tumors in 2 of 12 animals. Fixed tissue sections indicated that the tumors were relatively undifferentiated, but had some epithelial cells. A portion of one of the tumors was used to prepare the tumor cell line SV40hpI-1. In adult F344 rats previously subjected to whole-body irradiation, inoculation of SV40hpI-1 cells produced tumors in 83% of the animals. Continued passage of the tumor cell line in irradiated rats produced a tumor in 1 animal which paralyzed its host. The cell line derived from this tumor was tumorigenic in nonirradiated adult hosts. In order to investigate the mechanism by which HSV-2 infection of isolated hepatocytes results in poor virus replication, "shut off" of host protein synthesis, and stimulation of incorporation of label into hepatocyte DNA, studies were initiated using HSV-2 mutants. Use of the mutants should enable us to determine the role of specific HSV-2 gene functions in these events. Preliminary data suggested that stimulation can occur in the absence of virus DNA synthesis.